<template>
  <div class="home-page">
    <div class="banner">
      <div class="container">
        <h1 class="logo-font">conduit</h1>
        <p>A place to share your knowledge.</p>
      </div>
    </div>

    <div class="container page">
      <div class="row">
        <div class="col-md-9">
          <div class="feed-toggle">
            <ul class="nav nav-pills outline-active">
              <li class="nav-item" v-if="user">
                <nuxt-link
                  class="nav-link"
                  :class="{
                    active: tab === 'your_feed'
                  }"
                  :to="{
                    name: 'home',
                    query: {
                      tab: 'your_feed',
                    },
                  }"
                  exact
                  >Your Feed</nuxt-link
                >
              </li>
              <li class="nav-item">
                <nuxt-link
                  class="nav-link"
                  :class="{
                    active: tab === 'global_feed'
                  }"
                  :to="{
                    name: 'home'
                  }"
                  exact
                  >Global Feed</nuxt-link
                >
              </li>
              <li class="nav-item" v-if="tag">
                <nuxt-link
                  class="nav-link"
                  :class="{
                    active: tab === 'tag'
                  }"
                  :to="{
                    name: 'home',
                    query: {
                      tab: 'tag',
                      tag: tag
                    },
                  }"
                  exact
                  >#{{ tag }}</nuxt-link
                >
              </li>
            </ul>
          </div>

          <div
            class="article-preview"
            v-for="article in articles"
            :key="article.slug"
          >
            <div class="article-meta">
              <nuxt-link
                :to="{
                  name: 'profile',
                  params: {
                    username: article.author.username,
                  },
                }"
                ><img :src="article.author.image"
              /></nuxt-link>
              <div class="info">
                <nuxt-link
                  :to="{
                    name: 'profile',
                    params: {
                      username: article.author.username,
                    },
                  }"
                >
                  {{ article.author.username }}
                </nuxt-link>
                <span class="date">{{ article.createdAt | date('MMM DD, YYYY') }}</span>
              </div>
              <button
                class="btn btn-outline-primary btn-sm pull-xs-right"
                :class="{ active: article.favorited }"
                @click="onFavorite(article)"
                :disabled="article.favoriteDisabled"
              >
                <i class="ion-heart"></i> {{ article.favoritesCount }}
              </button>
            </div>
            <nuxt-link
              class="preview-link"
              :to="{
                name: 'article',
                params: {
                  slug: article.slug,
                },
              }"
            >
              <h1>{{ article.title }}</h1>
              <p>{{ article.description }}</p>
              <span>Read more...</span>
            </nuxt-link>
          </div>
        </div>

        <div class="col-md-3">
          <div class="sidebar">
            <p>Popular Tags</p>
            <div class="tag-list">
              <nuxt-link
                :to="{
                  name: 'home',
                  query: {
                    tag: item,
                    tab: 'tag'
                  },
                }"
                class="tag-pill tag-default"
                v-for="item in tags"
                :key="item"
                >{{ item }}</nuxt-link
              >
            </div>
          </div>
        </div>

        <!-- 分页列表 -->
        <nav>
          <ul class="pagination">
            <li
              class="page-item"
              :class="{
                active: item === page,
              }"
              v-for="item in totalPage"
              :key="item"
            >
              <nuxt-link
                class="page-link"
                :to="{
                  name: 'home',
                  query: {
                    page: item,
                    tag: $route.query.tag,
                    tab: tab
                  },
                }"
                >{{ item }}</nuxt-link
              >
            </li>
          </ul>
        </nav>
        <!-- 分页列表 -->

      </div>
    </div>
  </div>
</template>

<script>
import { getArticles, getYourFeedArticles, addFavorite, deleteFavorite } from "@/api/article";
import { getTags } from "@/api/tag";
import { mapState } from "vuex";

export default {
  name: "HomeIndex",
  async asyncData({ query }) {
    // 获取文章列表
    const page = Number.parseInt(query.page || 1);
    const limit = 20;
    const tab = query.tab || 'global_feed'
    const tag = query.tag

    // 根据 tab 决定获取是否是获取关注用户的文章
    const loadArticles = tab === 'global_feed'
      ? getArticles
      : getYourFeedArticles

    /**
     * 将串行任务改成并行任务写法
     */
    // const { data } = await getArticles({
    //   limit,
    //   offset: (page - 1) * limit
    // });
    // // 获取标签列表
    // const { data: tagsData } =await getTags()

    // 并行异步任务
    const [articlesRes, tagsRes] = await Promise.all([
      loadArticles({
        limit,
        offset: (page - 1) * limit,
        tag: query.tag,
      }),
      getTags(),
    ]);

    const { articles, articlesCount } = articlesRes.data;
    const { tags } = tagsRes.data;

    // 增加点赞按钮不能点击标志
    articles.forEach(article => article.favoriteDisabled = false)

    return {
      articles, // 文章列表
      articlesCount, // 文章总数
      tags, // 标签列表
      limit, // 每页大小
      page, // 页码
      tab, // 选项卡
      tag // 数据标签
    };
  },
  // watchQuery 可以监听 query 参数字符串的变化重新调用所有组件方法 (asyncData, fetch, validate, layout, ...)
  watchQuery: ["page", "tag", "tab"],
  computed: {
    ...mapState(["user"]),
    totalPage() {
      return Math.ceil(this.articlesCount / this.limit);
    },
  },
  methods: {
    async onFavorite (article) {
      // 改变点赞按钮为不可点击状态
      article.favoriteDisabled = true
      if (article.favorited) {
        // 取消点赞
        await deleteFavorite(article.slug)
        article.favorited = false
        article.favoritesCount -= 1
      } else {
        // 添加点赞
        await addFavorite(article.slug)
        article.favorited = true
        article.favoritesCount += 1
      }
      // 改变点赞按钮为可点击状态
      article.favoriteDisabled = false
    }
  }
};
</script>

<style>
</style>